Wash the blackberries. In a medium saucepan, bring water and fruit to a boil. Lower the heat and simmer for 15 minutes.
Remove from heat. Pour through a fine mesh strainer to strain the hot liquid into a bowl or jar. Discard solids.
Stir the sugar into the blackberry mixture until sugar dissolves. Let cool to room temperature before using.
Blackberry Margarita
Pour some sugar on a plate. Rub a lime wedge around the edge of a glass. Roll the rim of the glass in the sugar to coat the rim.
In a cocktail shaker filled with ice, add tequila, triple sec, blackberry syrup and lime juice. Shake well.
Strain into a margarita or rocks glass with ice.
Notes
If you want to make a non-alcoholic Blackberry Margarita, use a zero-proof spirit in place of the tequila and orange juice in place of triple sec.For added flavor, use reposado tequila instead of blanco. Spicy tequila would also be a nice touch!